EVOLUTION OF THE CARBON NANOTUBE BUNDLE STRUCTURE UNDER BIAXIAL AND SHEAR STRAINS

Abstract

Close packed carbon nanotube bundles are materials with highly deformable elements, for which unusual deformation mechanisms are expected. Structural evolution of the zigzag carbon nanotube bundle subjected to biaxial lateral compression with the subsequent shear straining is studied under plane strain conditions using the chain model with a reduced number of degrees of freedom. Biaxial compression results in bending of carbon nanotubes walls and formation of the characteristic pattern, when nanotube cross-sections are inclined in the opposite directions alternatively in the parallel close-packed rows. Subsequent shearing up to a certain shear strain leads to an appearance of shear bands and vortex-like displacements. Stress components and potential energy as the functions of shear strain for different values of the biaxial volumetric strain are analyzed in detail. A new mechanism of carbon nanotube bundle shear deformation through cooperative, vortex-like displacements of nanotube cross sections is reported.